The speakers in the doors are the same size front and back, 6.5 is the biggest i think can fit in. Best thing to do about a TRD intake would be to canvass the members here and keep an eye on ebay....TRD stopped production/imports into aus or something like that a while ago, have you thought about ingen? look at the CAI buyers guide in the topics here, is very helpful. As to the door trim its just a few clip-thingys they just pop out given a bit of muscle, start down in he bottom corner opposite the speakers, then lift vertically to clear the window frame, its pretty straight forward. The centre facia, i start with the gear shifter cover where the cigarette lighter is, just pop that out (clip-thingys again) take the wires out of the back, and just work upwards, pop out the A/C controls and take the wires out of the back as well, then the top A/C vents pop out too then just a 10mm socket screwdriver and a phillips-head screwdriver and its easy, u'll probly want to go to Autobarns or supersh!t to get adaptor plugs...just ask you friendly neighbourhood shop assistant and he should be able to help.